The present invention relates to a lubricating system for a multi-cylinder reciprocating piston engine in which at least one oil pump which is driven by the crankshaft thereof, is accommodated in an end face oil pump housing threadably connected to the engine housing and which delivers lubricating oil from an oil reservoir tank by way of a filter and distribution channels to the bearing places of the crankshaft, of the cam shaft and to other lubricating places.
In such a lubricating system as disclosed in the DE-PS No. 32 03 312, a housing for a lubricating oil pump is formed in an end cover that is flangedly connected to the engine housing. The lubricating oil pump and the gear driving the same are disposed coaxially to the crankshaft. The lubricating oil pump sucks the oil out of a reservoir tank and feeds the same by way of distribution channels and an oil filter that is attached to the outer side surface of the end cover, to the lubricating places of the engine. This lubricating system is quite well suited for a low-speed engine. However, in a high-speed engine considerable noises would emanate from the oil pump housing formed by the bending-soft end cover.
It is therefore the object of the present invention to so construct a lubricating system for a reciprocating piston engine that it enables an adequate lubrication also at highest engine rotational speed without excessive noise radiation. The oil pump housing is thereby to be compact, form-stable and to be assemblable at the engine housing in a simple manner, and the lubricating system is to be utilizable at the same time for an oil sump lubrication and for a dry sump lubrication.
The underlying problems are solved according to the present invention in that the oil pump housing is constructed as a preassemblable structural unit closed in itself and consisting of two cast housing parts threadably secured at their separating surface and centered with respect to one another. If the oil pump is closely surrounded by a housing which is composed of two mutually centered and mutually threadably connected housing parts, a fitting-accurate and stable bearing support can be achieved for the pump wheel so that the noise formation is minimal and a noise radiation from a large-area end cover is avoided. A simple and reliable assembly is made possible in that the oil pump housing is constructed together with the oil pump and its bearing support as preassemblable structural unit. According to another feature of the present invention, after the attachment of this structural unit at the engine housing, the inner part of the oil pump housing is centered in the engine housing and is sealed radially, while the outer housing abuts end face sealed at the engine housing and is threadably connected together with the same.
Such a lubricating arrangement is suited both for an oil sump lubrication in which it sucks off oil out of the crankcase as also for a dry sump lubrication in which a separate lubricating oil reservoir tank is provided. In order to achieve a further noise reduction and an improvement of the oil delivery, provision is made according to another feature of the present invention to utilize in lieu of one large oil pump which acts at the same time as suction and pressure pump, two smaller oil pumps, of which one operates as suction pump and the other as pressure pump. According to still a further object of the present invention, a cylindrical oil filter is located centrally between the horizontally installed pressure pump and the suction pump disposed parallel thereto with the oil further disposed transversely with respect to the two pumps, whose filter cartridge can be disassembled in the downward direction. The housings of the oil pumps and of the oil filter are fitted-in into the outer contour of the oil pump housing cast of magnesium whereby the outer diameter of the filter housing is approximately equal to the thickness of the oil pump housing and the length of the filter housing is approximately equal to the height of the oil pump housing.
According to still another object of the present invention, a regulator housing is cast-on to the top side of the oil pump housing approximately aligned to the filter housing, which contains a pressure regulator adapted to be removed in the upward direction. The combination of these different aggregates in a single cast part makes it possible to cast all connecting channels for the lubricating oil into the same so that pipes or hoses can be dispensed with.